Process of treating the spent liquor of paper-mills.



I. KITSEE. PROCESS OF TREATING THE SPENT LIQUOR OF PAPER MILLS.A'n'moumx rnmn FEB. 20,1902. nnsswsn APR. 8, 1900.

942,207. Pat ented Dec. 7, i909.

WITNESSES r v INVENTOR amawz Z ISIDOB KITSEE, OF PHILADELPHIA,PENNSYLVANIA.-

PROCESS OF TREATING THE SPENT LIQUOR OF PAPER-MILLS.

Specification of Letters Patent.

Patented Dec. 7, 1909.

Application filed l'ebrueryzo, 1908, Serial No. 144,347. Renewed April8, 1909. Serial No. 488,788.

To all whom it may concern:

Be it known that I IsmoR Krrsnn, of the city and county of Ihiladelphia,State of Pennsylvania, have invented a certain new and useful Imrovement in the Process of Treatin the pent Liquor of Paper or Pulpills, of which the following is a specific'atio My invention relates toan improvement in the process of treating the spent li uor of paper orpulp mills, so as to be ena led to extract from said spent liquor thecaustic or alkali, and also to extract from said liquor the resinous andallied substances, and

it is the further, aim ofmy invention to prepare the reclaimed causticor alkall in a manner so as toimpart to the same the causticitynecessary for its reemployment.

In the rocess of producing aper from wooden r, the wood is eit er cut orground into pieces of convenient size and then boiled in a caustic oralkaline solution. Through this process, all the intercellulosesubstance, such as'resinous material, etc., is extracted from the woodand dissolved in the caustic or alkaline solution. To reclaim thecaustic ,or alkali, the solution is boiled down to a syrupy consistencyand then fired, whereby the resinous matter becomes entirely carbonized.The residue is again dis-- solved in water, and then filtered. In thisprocess, the resinous material is not only lost, but it requires a greatamount of fuel to'carbonize or burn up the same, so as to be* enabled toreclaim the alkaline or caustic matter. In this process, a great amountof.

hydrated alkali has always to be added to kee up the causticity, as itis technically cal ed. It is one of the aims of my invention, to

' vent its use.

other by a porous septum. Each of these compartments is provided with anelectrode, the electrode of the negative compartment may consist ofcopper, iron or lead or other suitable conductor, but the electrode ofthe positive compartment should consist if possible of a material notinjuriously affected by the electrolyzing action of the current, suchfor instance as platinum, but as the price of this metal may be a bar toemploy-' mg the same, lead, graphite, or carbon may be'used instead. Iam well aware that the lead will slowly oxidize and may even impart tothe liquid in the positive compartment a reddish tint, but as the liquidcontents of this compartment will not be used for any other purpose thanfor separating the resinous maternal, this action of the current willnot be detrimental enou h to pre- The' connection 0% the two electrodesas to the charging current is as .usual. The negative electrode or theelec-.

trode contained in the negative compartment is connected to the negativepole of the char ing circuit, and the electrode contained in t epositive compartment is connected to the ositive pole of the chargingcircuit. In a s ort time, the test will show that the contents of thenegative compartment has acquired a stronger alkaline re-action than thecontents of the positive compartment. In my experiments, I havegenerally added a slight amount of sulfuric acid in the positive comartment, so as to hasten the separation of t 1e resinous matter from itsliquid contents. After the current has passed through the electrolyticaparatus for a suflicient length of time, it was ound that all thealkali hadaccumulated in the negative compartment and all the acid inthe positive compartment, but the liquid in the ne ative compartmentremained surcharget? with various matters and it needed a second processto clarify this liquid. In my later experiments, .I therefore used thefollowing arrangement :I placed the spent liquoronly in the positivecompartment of the. electrolytic apparatus containing two compartments,using in the second or negative compartment ,plain water, and as thiswater has to be made more conductlng and as it was necessary to add tothe resulting caustic liquid of the former e rperiments more caustic, Iadded to the plam water a 'chlorid of sodium, known in commerce, as

positive compartment becomes aciduous and the resinous material therebycoagulates and separates out of the liquid. Third,t he liquor in thenegative compartment remains clear and unadulterated. Fourth,thenecessary degree of causticity is imparted to the liquid. But, it isobvious, that to regain for the negative compartment the degree ofcausticity required will take agreater length of time than if part ofthe spent liquor would have been therein. Andlt is a matter-to bedecided by the person in charge of the plant, if the first method shouldbe employed or if the second method is preferred 1n his particular case.In both cases, if

the negative compartment consists at the beginning of pure! water withan addition of salt, or consists'gin the be inning of spent liquor withanaddition 0 salt, the result- 'ant product is:, in the negativecompartment, an alkali, and in the positive comthat it will, in itsgaseous state, leave the tents of the ed, I would suggest that tpartment, the resinous material mostl floating on top, because of itsfine subdiv1-. sion, and the chlorin or chlorinated liquid. In suchcases, where the spent liquor has only traces of resinous material, andwhere the causticity should be of a greater degree, the chlorin eneratedin the positive compartment wfil be in such superabundance compartmentand it is therefore advisable, for the purpose of protecting theatmosphere, as well as for the purpose of saving the chlorin as, toclose the positive compartment an to provide the same with an outletpipe, preferably passin into a tank of water. This water, as we as theconositive compartment, after being cleared rom the resmous and alliedmatter, may then be used for the purpose of bleaching as is well knownby persons versed in the art. a For such mills where my process isadapte usual high temperature should not be employed in the treatment ofthe. wood fiber with the caustic liquor, as the lower the temperatureadopted, the more perfect will be the state of the reclaimed resinousand other matter, and the better quality of the product more than repaysfor the greater length of time required.

In the accompanying drawing, in which Figure 1 illustrates in a partialsection and partial diagram one arrangement in which an electrolytic aparatus is used to recover simultaneously e caustic and resinoussubstances, and in which Fig. 2 is a plan view of the material designedtor-strain the 1iquid,A is the tank containing the spent liquor B, thistank is provided with the pi e G connected 'with the interposition of te valve D to the pipe E, havmg the branch- %ipes E and It, provided withthe valves 1 and D respectively.

The electrolytic ap aratus consists of the containing vessel G, lieredivided into two compartments B and B each filled with the necessaliquid. These compartments are divided y the porous (partition C thecompartment B is provi ed with the electrode H, and the compartment B isprovided with the electrode I. These two compartments are also providedwith the removable rece tacles g and g respectively. These remova blereceptacles preferably consist of a material, such as a very closelywoven wire gauze or textile, so as to be able to collect the mechanicalimpurities contained in the liquid to be electrolyzed, and also so as tobe able to collect the resinous material and to have the drained-outliquids as pure and clarified as possible; for this reason I have alsoprovided the guards J, J,

woven wire gauze or textile. The compart-' ment B is provided with theoutlet pipe F containing the valve D and the compartment B is providedwith the outlet pipe F containing the valve D. It is obvious that thearrangement of this electrolytic ap aratus may differ and I haveillustrat a form which I have found well adaptedfor the urpose.

aving now described my invention, what I claim asnew'and desire tosecure by Letters Patent is 1. The process of treatin s ent liquor frompa er or pulp mills w ic comprises placing t e spent liquor in thepositive compartment of an electrolytic apparatus, in placing a solutionof salt in the negative compartment of said apparatus, in sendingcurrents of electricity through said compartments whereby the solutionin the ne ative compartment becomes alkaline and t e intercellulose andresinous material is retained in the positive compartment.

2. The process of treatin s ent liquor from paper or pulp mills w iclicomprises subjecting said spent liquor to the action of an electriccurrent in the positive compartment of an electrolytic ap aratus, thenegative compartment of said tainin a second conducting fluld.

3. e process of recovering the caustic apparatus con- 942,207 H n a andresinous matter Of the spenfi liquor from ne'sses, this seventeenth dayof February,

paper 01" pulp 1mills, 'vLhich cldmpnses m1ak- A. D. 1903. V

m said spent iquort e ano yte in an'e ec- I tri c apparatus and sendingcurrents of elec- ISIDOR KITSEE' 5 tricity through said apparatus.-Witnesses:

. In testimony whereof, I hereby sign my I EDITH R. STILLEY,

name in the presence of two subscribing wit- 1 CHAs. KRESSENBUCH.

